1. Technical Field of Invention
The present invention generally relates to a modified glycol coolant circuit within a motor vehicle having a coolant/refrigerant heat exchanger for thermal coupling of a cooling plant/heat pump with the coolant circuit, whereby the glycol circuit is adapted to the requirements of a heat pump for the heating of the interior passenger compartment of the motor vehicle with a glycol/water mixture as the heat carrier.
2. Description of the Prior Art
Cooling plants and heat pumps are utilized to cool or heat an interior space. The varying weather conditions caused by the sequence of seasons frequently require a heating system in winter and transitional periods and a cooling system in summer.
Prior art devices have been developed comprising the combination of a heat pump and a cooling plant to alternately provide heating or cooling to interior rooms of a building or to provide heating or cooling to the interior passenger compartment of an automotive vehicle.
Typically, in an automotive vehicle, heat from the engine is used to heat the interior of the vehicle. Modern combustion engines and electric motors tend to produce smaller and smaller amounts of waste heat. Therefore, future vehicle engines will yield sufficient amounts of heat to heat the passenger compartment, but not at the temperature level required. Particularly in winter, the cold-start phase is a problem. In some current diesel engine vehicles, supplementary heating systems with heater plugs, resistance heating systems, or fuel-fired burners have been provided, to supplement the heat provided by the engine.
Many automotive vehicles are equipped with a cooling plant to air condition the passenger compartment in hot weather situations. One alternative to using a supplementary heating system of improve the heating of the interior passenger compartment within the vehicle is to alternatively use the cooling plant as a heat pump in cold weather situations.
Prior art devices have combined cooling plants and heat pumps for use within automotive vehicles. The heat of the environment is used as a heat source, and alternatively, when needed, the temperature of the engine""s waste heat is increased by the heat pump. For the use of a combined cooling plant/heat pump, where a glycol coolant circuit is the heat source of the heat pump, the cooling circuit must be adapted for this use.
Referring to FIG. 1, a prior art coolant circuit is divided into a first circuit 1 and a second circuit 2. A glycol/water mixture flows through the coolant circuit and is moved by a pump 7. The glycol/water mixture cools the engine 16, thereby assimilating heat and continuously flowing within the first circuit 1. A heat exchanger 3 of the heating system is positioned within the first circuit, whereby heat is absorbed from the glycol/water mixture and used to heat the passenger compartment of an automotive vehicle. A thermostat 4 is adapted to open when the temperature of the glycol/water mixture exceeds a pre-determined value. Once the thermostat 4 is opened, the glycol/water mixture is allowed to flow into the second circuit 2. A radiator is positioned within the second circuit 2 and is adapted to radiate heat from the glycol/water mixture to the environment, thereby removing waste heat of the engine to the environment.
In addition, the refrigerant circuit, which preferably uses carbon dioxide as refrigerant, is designed according to the state-of-the-art such that both the cooling plant operational mode and the heat pump operational mode are possible.
The refrigerant circuit and the coolant circuit each have a number of components. The components must be meticulously assembled, either manually or by automated methods, because leakage in the system will prevent the system from working properly. Space limitations add difficulties to the assembly of these components.
Therefore, it is the objective of this invention to provide a coolant circuit having features to transfer the heat to a refrigerant circuit wherein the coolant circuit optimizes size, maintenance, and assembly considerations, and the coolant circuit acts as the heat source for a heat pump to heat the passenger compartment of a motor vehicle.
The disadvantages of the prior art are overcome by providing a coolant circuit for a motor vehicle with a coolant/refrigerant heat exchanger for thermal coupling of a cooling plant/heat pump to the coolant circuit. The coolant circuit is preferably a glycol circuit, whereby the glycol circuit according to the invention is adapted to the requirements of a heat pump for the heating of the passenger compartment of the motor vehicle with a glycol/water mixture as heat carrier, wherein the glycol circuit is thermally coupled over the glycol/refrigerant heat exchanger to the refrigerant circuit of the cooling plant/heat pump such that the glycol/refrigerant heat exchanger together with the external heat exchanger, the radiator, the accumulator/collector, and internal heat exchanger forms a space-saving, easy to assembly and low maintenance heat exchanger module with integrated connection lines for heat transfer from the glycol circuit to the refrigerant circuit.
In another aspect of the present invention, a high-pressure selector valve and a low-pressure selector valve of the refrigerant circuit are integrated into the heat exchanger module. The design of the coolant and refrigerant circuits according to the present invention allows the number of connection ports to be reduced, and the supplier can pre-assemble the heat exchanger module using dedicated assembly technology. These features result in cost savings and enhanced quality. Additionally, particularly in winter, the ride comfort improves due to the coupling according to the present invention of the coolant and refrigerant circuits and use of the heat pump, as the desired temperature in the interior of the passenger compartment can be achieved more rapidly.
Further details, features and advantages of the invention ensue from the following description of examples of embodiments with reference to the drawings.